U.S. patent application number 14/660218 was filed with the patent office on 2015-09-24 for method and technical equipment for short range data transmission.
The applicant listed for this patent is Silicon Laboratories Finland Oy. Invention is credited to Jere Knaappila.
Application Number | 20150271628 14/660218 |
Document ID | / |
Family ID | 52875652 |
Filed Date | 2015-09-24 |
United States Patent
Application |
20150271628 |
Kind Code |
A1 |
Knaappila; Jere |
September 24, 2015 |
Method And Technical Equipment For Short Range Data
Transmission
Abstract
The application relates to a method, an apparatus and a computer
program product. The method comprises adjusting dynamically a
sensitivity of a receiver from a default sensitivity to a low
sensitivity; wherein the adjusting is based on the signal strength
of at least one existing connection or at least one previous
connection; receiving only such packets by the receiver which are
available with the low sensitivity.
Inventors: |
Knaappila; Jere; (Evitskog,
FI) |
|
Applicant: |
Name |
City |
State |
Country |
Type |
Silicon Laboratories Finland Oy |
Espoo |
|
FI |
|
|
Family ID: |
52875652 |
Appl. No.: |
14/660218 |
Filed: |
March 17, 2015 |
Current U.S.
Class: |
455/41.2 |
Current CPC
Class: |
H04W 24/10 20130101;
H04W 84/18 20130101; H04W 4/80 20180201; H04W 76/10 20180201 |
International
Class: |
H04W 4/00 20060101
H04W004/00; H04W 76/02 20060101 H04W076/02; H04W 24/10 20060101
H04W024/10; H04W 76/04 20060101 H04W076/04 |
Foreign Application Data
Date |
Code |
Application Number |
Mar 18, 2014 |
FI |
20145250 |
Claims
1. A method, comprising: adjusting dynamically a sensitivity of a
receiver from a default sensitivity to a low sensitivity; wherein
the adjusting is based on the signal strength of at least one
existing connection or at least one previous connection; and
receiving only such packets by the receiver which are available
with the low sensitivity.
2. The method according to claim 1, wherein the adjusting of the
sensitivity based on the signal strength of at least one existing
connection comprises: a) receiving a first packet from a sender
with default sensitivity by the receiver; b) determining if a
saturation occurs in the receiver due to the received packet, and
if so; decreasing the sensitivity from the default sensitivity to
the low sensitivity, receiving at least one second packet with the
low sensitivity, and going to step b); c) otherwise determining
signal strength of the received packet; and d) reporting the signal
strength.
3. The method according to claim 2, wherein the method comprises
determining a distance between the receiver and the sender using
the determined signal strength.
4. The method according to claim 1, wherein the method is carried
out in a Bluetooth low energy enabled device.
5. An apparatus comprising at least a processor and memory, wherein
the apparatus is configured to: adjust dynamically a sensitivity
from a default sensitivity to a low sensitivity; wherein the
adjusting is based on the signal strength of at least one existing
connection or at least one previous connection; and receiving only
such packets which are available with the low sensitivity.
6. The apparatus according to claim 5, wherein the apparatus is
configured to adjust the sensitivity based on the signal strength
of at least one existing connection by: a) receiving a first packet
from a sender with default sensitivity; b) determining if a
saturation occurs in the apparatus due to the received packet, and
if so: decreasing the sensitivity from the default sensitivity to
the low sensitivity, receiving at least one second packet with the
low sensitivity, and going to step b); c) otherwise determining
signal strength of the received packet; and d) reporting the signal
strength.
7. The apparatus according to claim 6, wherein the apparatus is
configured to determine a distance between the apparatus and the
sender using the determined signal strength.
8. The apparatus according to claim 5, wherein the apparatus is a
Bluetooth low energy enabled device.
9. A computer program product embodied on a computer readable
medium comprising computer program code configured to, when
executed on at least one processor, cause an apparatus or a system
to: adjust dynamically a sensitivity from a default sensitivity to
a low sensitivity; wherein the adjusting is based on the signal
strength of at least one existing connection or at least one
previous connection; and receiving only such packets which are
available with the low sensitivity.
10. The computer program product according to claim 9, further
causing the apparatus or the system to adjust the sensitivity based
on the signal strength of at least one existing connection by: a)
receiving a first packet from a sender with default sensitivity; b)
determining if a saturation occurs in the receiver due to the
received packet, and if so: decreasing the sensitivity from the
default sensitivity to a low sensitivity, receiving at least one
second packet with the low sensitivity, and going to step b); c)
otherwise determining signal strength of the received packet; and
d) reporting the signal strength.
11. The method according to claim 2, wherein the method is carried
out in a Bluetooth low energy enabled device.
12. The method according to claim 3, wherein the method is carried
out in a Bluetooth low energy enabled device.
13. The apparatus according to claim 6, wherein the apparatus is a
Bluetooth low energy enabled device.
14. The apparatus according to claim 7, wherein the apparatus is a
Bluetooth low energy enabled device.
Description
[0001] This application claims priority to co-pending Finnish
patent application serial number 20145250 filed on Mar. 18, 2014,
the disclosure of which is incorporated herein by reference in its
entirety for all purposes.
TECHNICAL FIELD
[0002] The present application relates to Bluetooth modules. In
particular the present application relates to Bluetooth low
energy.
BACKGROUND
[0003] Bluetooth Low Energy (BLE) relates to Bluetooth wireless
radio technology. It has been designed for low-power and low
latency applications for wireless devices within short range.
Today, BLE applications can be found from healthcare, fitness,
security, smart energy, industrial automation and home
entertainment. However, BLE is not limited only those, but
increasingly more new applications utilizing BLE technology are
designed.
[0004] The difference between BLE and classic Bluetooth is that the
BLE devices consume remarkably less power for communication than
classic Bluetooth devices. In addition, the BLE is able to start
the data transmission much quicker than the classic Bluetooth. This
makes it possible to have BLE devices constantly on and to
communicate intermittently with other devices.
SUMMARY
[0005] Now there has been invented an improved method and technical
equipment implementing the method, by which sensitivity of a radio
can be adjusted, whereby also a high accuracy distances measurement
in both far and short distances can be implemented at the same time
using normal low energy radios. Various aspects of the invention
include a method, an apparatus, comprising a computer program
stored therein, which are characterized by what is stated in the
independent claims. Various embodiments of the invention are
disclosed in the dependent claims.
[0006] According to a first aspect, there is provided a method
comprising adjusting dynamically a sensitivity of a receiver from a
default sensitivity to a low sensitivity; wherein the adjusting is
based on the signal strength of at least one existing connection or
at least one previous connection; and receiving only such packets
by the receiver which are available with the low sensitivity.
[0007] According to a second aspect, there is provided an apparatus
comprising at least processing means and memory means, wherein the
apparatus is configured to adjust dynamically a sensitivity from a
default sensitivity to a low sensitivity; wherein the adjusting is
based on the signal strength of at least one existing connection or
at least one previous connection; and receiving only such packets
which are available with the low sensitivity.
[0008] According to a third aspect, there is provided a computer
program product embodied on a computer readable medium comprising
computer program code configured to, when executed on at least one
processor, cause an apparatus or a system adjust dynamically a
sensitivity from a default sensitivity to a low sensitivity;
wherein the adjusting is based on the signal strength of at least
one existing connection or at least one previous connection; and
receiving only such packets which are available with the low
sensitivity.
[0009] According to an embodiment, the adjusting of the sensitivity
based on the signal strength of at least one existing connection
comprises receiving first packet from a sender with default
sensitivity by the receiver; determining if a saturation occurs in
the receiver due to the received packet, and if so, decreasing the
sensitivity from the default sensitivity to the low sensitivity,
and receiving at least one second packet with the low sensitivity,
and going to step of determining the saturation; otherwise
determining signal strength of the received packet; and reporting
the signal strength.
[0010] According to an embodiment, a distance between the receiver
and the sender is determined by means for the determined signal
strength.
[0011] According to an embodiment, the receiver is a Bluetooth low
energy enabled device.
DESCRIPTION OF THE DRAWINGS
[0012] In the following, various embodiments of the invention will
be described in more detail with reference to the appended
drawings, in which
[0013] FIG. 1 shows a Bluetooth smart module according to an
embodiment;
[0014] FIG. 2 shows a simplified block chart of a Bluetooth
module;
[0015] FIGS. 3a-3b shows an example of an advertising mode in a
Bluetooth system;
[0016] FIG. 4 shows an arrangement according to an embodiment;
[0017] FIG. 5 shows a method according to an embodiment;
[0018] FIG. 6 shows an example of a local device with various
sensitivity levels;
[0019] FIG. 7 shows an example of scanner device's operation during
advertisement;
[0020] FIG. 8 shows an example of master device's operation during
connection event; and
[0021] FIG. 9 shows an example of slave device's operation during
connection event.
DESCRIPTION OF EXAMPLE EMBODIMENTS
[0022] In the following, several embodiments of the invention will
be described in the context of adjusting a sensitivity of a device
in order to determine a received signal strength indication for
purposes of distance determination. It is to be noted, however,
that the invention is not limited to this. In fact, the different
embodiments have applications in any environment where device's
sensitivity is to be adjusted.
[0023] FIG. 1 illustrates an example of an electronic apparatus
100. According to an embodiment, the apparatus 100 is a Bluetooth
smart module that comprises application layer 110, host layer 120
and a Bluetooth (or BLE) controller 120. The application layer 110
comprises the apparatus related application(s) (e.g. heart rate,
proximity, blood pressure, time update, temperature, battery, . . .
), smart profiles, script and application programming interface
(API). The application is capable of reading sensor data e.g. from
heart rate sensor, and reporting the data to host layer for
transmitting the data by means of the Bluetooth (or BLE) controller
130. The host layer 120 comprises protocols running over the
connection. Host layer 120 also comprises data to be used in
advertisement profile (GATT), generic access profile (GAP),
attribute protocol (ATT), security manager (SM) and logical link
control and adaptation protocol (L2CAP). The Bluetooth (or BLE)
controller 130 comprises link layer, baseband and physical layer
(i.e. physical radio, radio frequency RF).
[0024] The link layer provides ultra-low power idle mode operation
and device discovery (i.e. connection mode and advertising mode
handling). The link layer also is in charge for packet transmission
and responding.
[0025] FIG. 2 illustrates an example of a BLE module available on
the market as a simplified block diagram. Central processing unit
and memory means with application data are located in segment 200.
A part of the link layer and physical layer are illustrated with
reference 210. This segment 210 contains elements, such as radio
registers, link layer engine, modulator-demodulator,
receiving-transmitting means, frequency synthesizer,
balancing-unbalancing unit (balun), antenna (ant).
[0026] In BLE technology one or more slave devices can be connected
to a master device. The master is able to communicate with one or
more slave devices, also simultaneously. To let the master know
about the slave devices, the slave devices (or at that point
"advertisers") periodically, at pseudo-random intervals, pass
advertisement packets which a scanner device (i.e. "scanner") is
scanning.
[0027] Advertisement packet types from the apparatus are
TABLE-US-00001 ADV_IND connectable undirected advertising event
ADV_DIRECT_IND connectable directed advertising event
ADV_NONCONN-IND non-connectable undirected advertising event
ADV_DISCOVER_IND discoverable undirected advertising event
[0028] Response packets from the scanning device to the
advertisement packets of the advertising device are
TABLE-US-00002 SCAN_REQ scan request for further information from
advertiser CONNECT_REQ connect request.
[0029] When an advertising device receiver SCAN_REQ from a scanning
device, the advertising device may give more information to the
scanning device by SCAN_RSP packet. SCAN_RSP packet may contain
information on the name of the advertising device and on the
services the advertising device is able to provide. However,
SCAN_RSP packet is not limited to carry only this information but
may contain other data as well or instead.
[0030] CONNECT_REQ packet contains data on transmit window size
defining timing window for first data packet, transmit window
offset that is off when the transmit window starts, connection
interval is the time between connection events, slave latency
defines number of times the slave can ignore connection events from
the master, connection timeout is maximum time between two
correctly received packets in the connection before link is
considered to be lost, hop sequence is a random number appointing
the starting point for a hop, channel map, CRC initialization
value.
[0031] When a scanner is connected to an advertiser, the advertiser
is called "a slave" and the scanner is called "a master". The state
for passing advertisement packets is called "advertising state" and
the state for connection is called "connected state". In both
states, data transfer occurs. Slave device may be a sensor or an
actuator, such as a temperature sensor, heart rate sensor, light
bulb, proximity sensor etc. Master device can be any electronic
device e.g. mobile phone, smart phone, personal digital assistant,
personal computer, laptop computer, tablet computer, etc. The
electronic device may be capable of collecting data and/or capable
of sending data to sensors. Additionally, the electronic device can
be a rather low-end device in some occasions.
[0032] Packets sent from a slave device in advertising mode
contains approximately 27 bytes of data and a slave address.
Packets from master device in advertisement channel contains only a
master address.
[0033] FIGS. 3a-3b illustrate technical background for advertising
modes. FIG. 3a illustrates a setup of device B to send
advertisement packets. FIG. 3b illustrates a situation, where
device B is sending packets and device A wishes to active scan.
Host A and host B are a master device and a slave device
respectively. LLA is link layer of the master device, i.e. host A,
and LLB is link layer of the slave device, i.e. host B. From FIG.
3b it is realized that SCAN_REQ packet from host A as a response to
an advertisement packet from link layer LLB of host B is
transmitted to link layer LLB of host B. As a response to SCAN_REQ
packet, the link layer LLB of the host B sends a SCAN_RESP packet
with data.
[0034] Connection between the master device and the slave device
can be formed by the master device sending CONNECT_REQ packet after
the slave advertisement packet.
[0035] BLE devices are capable of determining RSSI (Received Signal
Strength Indication) to measure a power of the received radio
signal. The RSSI can be calculated from any packets in
advertisement state or connected state The determined RSSI can also
be used e.g. for approximating the distance between two devices.
There are formulas to determine the distance by using RSSI,
however, in some cases the RSSI is not valid, whereby the distance
cannot be determined. For example, if the devices are too close
then the receiver may saturate and no valid RSSI is obtained. On
the other hand, if receiver sensitivity is lowered, the a signal
with low power is not received. For example, Texas Instruments
CC24540/1 (BLE) based devices have dynamic range of 63 dBm, and
receiver saturates if signal value is higher than minimum
dBm+63.
[0036] The present embodiments provide a solution by means of which
a sensitivity of a device can be adjusted, whereby e.g. a valid
RSSI can be obtained, and thus also more accurate distance between
two devices can be determined. The present embodiments also may use
sensitivity adjustment for other purposes also.
[0037] A first embodiment is illustrates with reference to FIG. 4
where the sensitivity of the radio is lowered in order to have a
valid RSSI. In FIG. 4, a link layer 410 of a device 400 receives a
first packet 425 from a device 450 by means of radio (RF) 420). The
first packet may be received during connection event or
advertisement interval. In the device 400, the radio 420 reports
the received signal strength RSSI to the link layer 410, and
determines whether the received signal strength is at maximum or
close to the maximum, which is an indication of that the radio 420
has saturated. If the radio 420 of the device 400 has saturated,
the device 400 lowers the sensitivity of the radio 420 for the
following packets. The sensitivity adjustment affects the gain
setting of the radio amplifier, which may be at first set to
maximum amplification. For adjusting the sensitivity to lower
sensitivity, a new gain setting of the radio amplifier should be
selected to be enough to receive next packet, but not cause a
saturation of the radio or not to lose the packets (with very low
sensitivity, the packets may not be seen).
[0038] When a packet is received such that the radio has not
saturated, RSSI is determined from it. This valid RSSI value is
reported to the link-layer, which may send it further up to the
application stack. Because of the sensitivity adjustment, the RSSI
has compensated the received sensitivity--and the upper layers sees
only valid RSSI values.
[0039] The valid RSSI values may be then used for determining the
distance between device 400 and device 450 by using the known
distance determination algorithms. The solution disclosed here
improves the accuracy of the distance measurement. Due to this, new
applications utilizing distance measurement can be developed. One
example of a new application is a lock configured to be opened with
a mobile device. In such an example, the lock must not open if the
mobile device is close to the door, but only when the mobile device
is almost touching the lock. Today, the receiver saturates when the
transmitter is half meters away, and no accurate distance
determination can be made. Therefore, such an application cannot be
implemented with the technology prior the application.
[0040] The valid RSSI value can be used for approximating the
distance. Based on that, the different triggers may take place. The
advantage of the solution is that the low sensitivity does not
unnecessarily wake up the upper layer of the Bluetooth module. This
means that the Bluetooth module scanning may not "see" the whole
device until the other device is close to enough. Or vice versa,
the advertiser device does not see the SCAN_REQ until the scanner
device is close enough. This has a power consumption benefit in
addition to the accuracy and usability benefit.
[0041] FIG. 5 illustrates a method according to the previous
example as a flowchart. In this embodiment, the method comprises
[0042] receiving first packet with default sensitivity 510; [0043]
detecting whether saturation occurs 520; [0044] if so, decreasing
sensitivity from default sensitivity to a decreased sensitivity
550, and receiving next packet with the decreased sensitivity 560.
The method continues from the saturation detection step 520; [0045]
if saturation has not occurred, signal strength of the received
packet is determined 530, and the determined signal strength of the
received packet is reported 540.
[0046] FIG. 6 illustrates an example of a use case. There is a
local device 610 in the center. Also remote devices 620, 630, 640,
650 are illustrated in the figure. FIG. 6 illustrates with which
level of sensitivity the local device 610 is able receive packets
from the remote devices without saturation in the radio. For
example, in order to receive packets from remote device 620 from
which RSSI can be determined, the local device 610 needs to have a
low sensitivity. Further, in order to receive packets from remote
device 630 from which RSSI can be determined, the local device 610
needs to receive packets from remote device 630 with medium
sensitivity. However, if the sensitivity is low, the local device
may not see the remote device 630 at all. Yet, further packets from
remote device 640 for determining RSSI are received with maximum
sensitivity. Remote device 650, on the other hand, is out of
range.
[0047] FIGS. 7-9 illustrates scanner's operation, master's
operation and slave's operation when utilizing the present
embodiment. It is to be noted, that the embodiments of the present
invention occurs either during connection event or advertisement
event. The connection interval or advertisement interval defines
how often the events occur. In addition, the examples discloses
embodiments where the sensitivity is lowered after getting the
packets. However, it is appreciated that the lowering may happen
prior any packet has been transmitted/received.
[0048] In these examples [0049] T_IFS=150.rho.s and [0050]
Adv_idx=Advertisement channel used: [0051] 37=2402 MHz [0052]
38=2426 MHz [0053] 39=2480 MHz
[0054] FIG. 7 illustrates an embodiment of scanner operation during
advertisement. ADV_IND are advertisement packets sent by an
advertising device. When the advertising event begins, the scanner
uses default sensitivity for scanning the advertising packets. When
receiving the advertising packet, the scanning device detects
saturation in the radio. The scanner sends a SCAN_REQ packet to the
advertising device and adjust the gain setting of the radio. Thus
SCAN_RSP packet from the advertising device is received with lower
sensitivity. This SCAN_RSP packet is used for determining RSSI, and
further the distance to the advertising device. Further advertising
packets are again received with default sensitivity.
[0055] FIG. 8 illustrates an embodiment of a master operation
during connection event. When connection event has started, the
master sends a packet 810 to a slave. Default sensitivity is used
for receiving a packet 820 from a slave. However, this may cause
saturation in the radio, whereby no valid RSSI can be determined.
Therefore, for receiving the response packet 840 to the next packet
830 the master had send to the slave, the master lowers the
sensitivity. The packet 840 can be used for determining the RSSI
and further the distance between the master device and the slave
device. If there is no more data to transmit, the connection event
is closed. Otherwise the connection event may continue and packets
are continuously received with the lower sensitivity.
[0056] FIG. 9 illustrates an embodiment of a slave operation during
connection event. When the connection event has started, the slave
receives a packet 910 from the master with default sensitivity.
This may cause saturation in the radio, whereby no valid RSSI can
be determined. The slave transmits a packet 920 to the master and
lowers the sensitivity. The next packet 930 that is received from
the master is received thus with lower sensitivity, and RSSI can be
determined from that packet 930. The slave responds to the packet
930 with packet 940. If there is no more data to transmit, the
connection event is closed. Otherwise the connection event may
continue and packets are continuously received with the lower
sensitivity.
[0057] A second embodiment is disclosed with reference to FIG. 6.
This example relates to sensitivity adjustment of a radio for other
purposes than RSSI measurement. The need for sensitivity adjustment
(e.g. decrease) may be based on the current use or prior use (i.e.
signal strength of at least one existing connection, or at least
one previous connection), where it has been detected that there are
too many devices 630, 640, 650 in sight of the local device 610.
This means that the radio sensitivity is too high. The local device
610 may lower the sensitivity so that the devices 630, 640, 650 are
filtered out from the range, and only device's 620 data
transmission is detected. By this the sensitivity adjustment is for
limiting traffic.
[0058] The various embodiments may provide advantages. For example,
the present embodiments provide higher accuracy BLE solution for
distance measurement in both far and short distances at the same
time. The adjustment of sensitivity improves accuracy in RSSI
distance measurement. Further, due to the sensitivity adjustment,
the data transmission of certain devices may easily be filtered
out.
[0059] The various embodiments of the invention can be implemented
with the help of computer program code that resides in a memory and
causes the relevant apparatuses to carry out the invention.
[0060] It is obvious that the present invention is not limited
solely to the above-presented embodiments, but it can be modified
within the scope of the appended claims.
* * * * *